fix: [finance] 계정과목 설정 모달 중복 코드 조회 수정

- AccountCode 모델에 BelongsToTenant trait 추가하여 테넌트별 필터링 적용
- accountCodeStore에서 하드코딩된 tenant_id를 세션 기반으로 변경

app/Http/Controllers/Finance/JournalEntryController.php

@@ -831,7 +831,7 @@ public function accountCodeStore(Request $request): JsonResponse
         $maxSort = AccountCode::max('sort_order') ?? 0;
 
         $accountCode = AccountCode::create([
-            'tenant_id' => 1,
+            'tenant_id' => session('selected_tenant_id', 1),
             'code' => $validated['code'],
             'name' => $validated['name'],
             'category' => $validated['category'] ?? null,

app/Models/Barobill/AccountCode.php

@@ -3,6 +3,7 @@
 namespace App\Models\Barobill;
 
 use App\Models\Tenants\Tenant;
+use App\Traits\BelongsToTenant;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 
@@ -11,6 +12,7 @@
  */
 class AccountCode extends Model
 {
+    use BelongsToTenant;
     protected $table = 'account_codes';
 
     protected $fillable = [